A communication system that performs various processes by connecting multiple communication devices with a communication line and performing data exchange among the multiple communication devices is used in various fields. For example, in the field of vehicle-mounted LANs (Local Area Networks) that are installed in vehicles, multiple ECUs (Electronic Control Units) that each perform different processing are mounted on a vehicle. Due to the multiple ECUs exchanging data with each other, various functions are realized as a system. Communication devices have gained more functions and more advanced functions in order for systems to have more functions and more advanced functions, and this has been accompanied by an increase in the number of communication devices in a system and an increase in the amount of data exchanged between the communication devices. Thus the communication load has increased. Because of this, a configuration is commonly employed in which the communication devices are divided into multiple groups, multiple communication devices in a group are connected by a common communication line and data is exchanged as an increase in the communication load is suppressed by a relay device such as a gateway relaying the exchange of data between groups.
For example, JP 2002-261790A proposes a vehicle-mounted network system having a configuration in which multiple vehicle-mounted modules having standard interfaces and CPUs (Central Processing Units) that process information via the interface are connected to an information processing LAN on a vehicle, and a vehicle-mounted gateway integrates communication between the multiple vehicle-mounted modules, and the vehicle interior and exterior.
Also, various functions have been furthermore realized due to wireless communication being performed with an external device by an ECU that is installed in a vehicle. In the vehicle-mounted network system in JP 2002-261790A as well, a function of performing communication with external devices is included in the vehicle-mounted gateway.
JP 2002-274293A proposes a vehicle management system in which a management computer installed in a vehicle and a vehicle information terminal detachably connected to the management computer are included, and a management computer performs personal verification and the like with an external device based on information registered on a personal ID (Identifier) card that is inserted into the vehicle information terminal.